The invention relates to edible shaped bodies based on plastifiable biopolymers, cleavage products or derivatives thereof and/or synthetic polymers made from natural monomers. They are mainly used as packaging films, and sausage casings.
As edible sausage casings, there have proved useful, in addition to natural casings (for bockwurst especially sheep gut), only collagen films and tubes (DE-B 17 92 627 and U.S. Pat. No. 3,535,125). Edible casings based on calcium alginate (DE-B 12 13 211) have not been able to establish themselves.
Edible collagen films and tubes are produced from cattle hides by a very complex and environmentally-polluting process. The hides are digested with acids (e.g. lactic acid) until the fibrils are obtained; the high-viscosity mass is extruded and precipitated and consolidated slowly and compactly using gaseous NH3 or with NH4OH. During drying, crosslinking (curing) then takes place, which strengthens the products to the extent that they withstand the scalding process without any significant loss of mechanical stability.
In contrast, it has not been possible to give the alginate-based sausage casings the necessary stability. In the case of these casings, owing to the action of the sausage emulsion and the brine, the poorly soluble calcium salt is gradually converted into the readily soluble sodium salt of alginic acid. The casings as a result lose their strength.